Help! mastering related question..methinks

Hmm. Here's a newbie question for ya: Why is it that a track I'm making sounds really powerful and overall good through some studio monitior headphones..and absolutely LIMP and crappy via a regular stereo system( crap amp + two 2 1/2 foot high speakers? Is it an issue of mastering? (as the track is not even finished, let alone mastered.) Or is it just a shitty stereo? Would mastering "fix" such a problem?

Hmm. Here's a newbie question for ya: Why is it that a track I'm making sounds really powerful and overall good through some studio monitior headphones..and absolutely LIMP and crappy via a regular stereo system( crap amp + two 2 1/2 foot high speakers? Is it an issue of mastering? (as the track is not even finished, let alone mastered.) Or is it just a shitty stereo? Would mastering "fix" such a problem?

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Mixing On Headphones
What To Use & How To Do It
Published in SOS December 2003
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Technique : Recording/Mixing

It's often necessary to work on headphones in the home studio, even when mixing. So what headphones should you choose, and how do you go about getting the best results?
Hugh Robjohns

At one time or another, we all resort to using headphones while trying to assess a mix. There are numerous occasions when such a tactic is required: we might be working late at night where monitoring on loudspeakers is too antisocial; or perhaps we are recording on the move with portable equipment, so using loudspeakers becomes impractical. It might even be that the monitoring room has poor acoustics or that the monitors are unfamiliar, and we either don't trust or can't rely on what we are hearing from the speakers. It may also be that we are recording in the same room that we are monitoring in, so loudspeakers are, again, inappropriate. Whatever the reason, working with headphones is a common practice, and in this article I will work through some of the techniques that can make using headphones more reliable and productive.
The Pros & Cons Of Mixing On Headphones
The first thing to say is that, generally, headphone monitoring is almost always only a 'second best' option. The vast majority of recorded sound is intended for listening via loudspeakers and it is important to recognise this fact. The simple amplitude differences we encode our stereo signals with to provide positional information (via the ubiquitous pan pot) only create a believable impression of spatial positioning when auditioned via a pair of correctly sited loudspeakers.

Speaker listening is different from headphone listening, because not only can sound from each speaker reach the opposite ear, but there is also an important contribution made by reflected sound arriving at the listener's ears from different angles.
The way in which our ears interpret sounds from loudspeakers is inherently very different to that from simple headphones. Stereophony is an auditory illusion — much as watching 25 still pictures each second in rapid succession creates the visual illusion of naturally moving images. When listening to a loudspeaker, its direct sound inherently arrives at both ears, and if the speaker is positioned off to one side (consider the left-hand speaker in a stereo pair, for example), then its sound will reach the closer ear slightly earlier than it reaches the more distant one. The fixed time-of-arrival differences for each ear combine with the variable amplitude differences encoded between the channels of the stereo audio material, and fool our sense of hearing into perceiving different time-of-arrival information for each reproduced sound, and thus discrete directions.
Headphone listening works in a very different way. When wearing headphones, each ear can only hear the sound from its own earpiece — there is no natural way in which the sound from the left earpiece can reach the right ear, for example. As a result, the recorded amplitude differences between the left and right channels don't create the required time-of-arrival differences. The consequence is that most of us perceive sounds coming from inside our heads, spaced roughly on a line running from ear to ear.
There are a few systems which attempt to overcome this deficiency by trying to introduce the crosstalk effects inherent in loudspeaker monitoring. However, emulating a loudspeaker listening environment on headphones is more complex than simply bleeding a little bit of each channel into the opposite earpiece. The crosstalk has to be delayed by an appropriate amount and be spectrally shaped to reflect the natural acoustic artefacts introduced when sounds pass around the human head. This combination of processing is often referred to as 'head-related transfer functions' or HRTF, but I am not aware of any commercial examples that work well enough to be considered for accurate mixing duties. Having said that, the increasingly sophisticated DSP process of convolution has a lot to offer in this context, and at least one extremely promising experimental system has been developed, as described in the 'Binaural Room Simulation' box.
The upshot is that if we are to use headphones for critical monitoring we are going to have to learn how to interpret what he hear and relate it to the effects portrayed over conventional loudspeakers.
Surround Mixing On Headphones: Developing The Binaural Room Simulator
If mixing stereo in headphones is difficult enough, how on earth can we hope to mix surround sound? Well, there is a solution, but at present it is impracticably expensive and remains a developmental project. The German research institute, the IRT and Studer have co-developed a Binaural Room Simulator (BRS). Essentially a pair of very accurate stereo headphones fitted with a positioning sensor which tells the apparatus which way the operator is facing. This is actually one of the most expensive elements of the system, but is crucial to its effectiveness.
The system involves two separate stages — a programming phase and a reproduction phase. In the programming phase, a dummy head (such as Neumann's KU100) is placed in the ideal listening position of a real control room. Special impulse test signals are then reproduced over each loudspeaker in turn and the signals captured by the two microphones placed in the 'ears' of the dummy head are stored for later analysis. This process is then repeated with the dummy head rotated in small increments (say, five degrees) over a ±45 degree range. The stored data is then translated into highly detailed convolution blueprints of how the specific monitoring room reacts to each surround sound channel.
The reproduction phase uses this convolution data to process each of the input surround channel signals to generate the corresponding stereo binaural sound field, and all of the binaural sound fields for each channel are combined before presenting them to the stereo headphone earpieces. The position sensor on the headphones tells the convolution processors which particular set of data to use, so that, as the user moves his or her head, the corresponding convolution data is applied, and the perceived sound stage remains stationary for the listener, just as it would in real life. Although this adds a huge amount of extra complexity to the system it was actually found to be an essential requirement if the illusion of listening to a real surround sound monitoring system were to work reliably.
The huge amount of processing power required to convolve six channels of audio with sufficient accuracy and resolution for high-quality monitoring currently makes this approach too expensive for a viable commercial application, but a number of research units have been constructed and I have been fortunate enough to audition the system for myself. While it was possible to identify minor defects in the audio quality of the early system I auditioned, its ability to portray a totally believable and stable surround sound stage was amazing, and clearly this approach has a great deal to offer in the years to come.
Apparently its most recent practical outing was for the New Year's Day concert broadcast from Vienna at the start of this year. The state broadcaster, ORF, decided to launch a new surround-sound transmission service with this event. However, the sound control room area of their Outside Broadcast truck was far too small to set up a proper surround-sound monitoring system. So, the balance engineer employed the experimental Studer BRS system during rehearsals to establish the surround sound mix, and with great success.
This is certainly one technology to watch. As the cost of DSP continues to fall, this will suddenly become a more viable commercial proposition, whether for stereo or surround-sound applications. When it does, headphone monitoring will suddenly become far more accurate and dependable than conventional loudspeaker monitoring for those of us with less-than-perfect control-room acoustics. After all, the system could be programmed with convolutional data gathered from one or more of the best studio control rooms on the planet, which we could then all share from the comfort of our own home studios!
Differences Between Headphone & Speaker Monitoring
The most obvious difference between monitoring via headphones and loudspeakers is the impression of stereo positioning, assuming the use of conventional pan-pot amplitude-difference techniques. If using one of the more complex panning systems that involves time-of-arrival differences and even HRTF functions as well (something which is really only practical in some of the high-end digital consoles) then the imaging may translate more easily. In general, though, when listening via headphones the spatial image will be spread along a line running between the ears, and most definitely inside the head. We all get used to this fairly easily, but the real problem is that the linearity of the panning proportions is rather different from that experienced on loudspeakers. There is no simple way to adapt to this other than by building experience.

Panning in particular is very difficult to judge on headphones, so it's important to compare your perceptions of different panning amounts on headphones with the results on speakers in order to gain experience.
It takes a considerable time to be able to judge panning amounts over headphones. It's not impossible to do, but it is very hard. To be honest, I think most of us probably rely more on our eyes when mixing on headphones, noting the positions of the pan pots visually rather than judging positions with our ears, as we would when monitoring on loudspeakers. Of course, extremes of panning aren't the problem — its the 'in between' settings which are vague and difficult to tie down precisely. Even deciding on an accurate centre position can prove difficult for some people!
The trick is to practice first with a single source (best to use a mono signal with a broad frequency spectrum) and compare the position you perceive when monitoring in headphones with the position as perceived over loudspeakers. Once you get used to how these two things relate, you can then relate them to the specific panning law of the mixer you're using — panning laws will vary with different equipment.
Another major difference between headphone and loudspeaker monitoring is the way the brain processes the information it receives through the ears. With loudspeaker monitoring, because both ears hear both sources, the brain processes the information it receives jointly and a kind of stereo masking function applies. However, when listening to headphones, the brain processes the data in a completely different way, handling information from each ear independently, so a degree of 'unmasking' occurs. The result is that certain elements in the mix — or abrupt changes to the mix — that may be inaudible when auditioned on loudspeakers become glaringly obvious on headphones. And, occasionally, the reverse is also true.
Finally, the obvious lack of any physical impact (or 'vibration' for the more genteel) from low-frequency signals may create the impression that the low end of the mix is lacking in some way — and this can be made worse by the rather odd character of bass frequencies in some headphones.
Using Headphones Safely
Obviously, listening to loud sounds over prolonged periods is not a good idea, because hearing damage is cumulative and can be permanent. To make matters worse, the better the monitoring equipment (in other words, the lower its distortion levels) the quieter it seems to be, so it's easier to end up listening at dangerously high levels. With loudspeakers, even really good ones, you tend to know when it's getting too loud, because your internal organs start being reorganised with each beat of the bass drum, the ornaments start falling off the mantelpiece, and the neighbours send for the Environmental Health officers! None of these side effects happen when using headphones, and even the blood spurting from ruptured eardrums is concealed by the headphone earpieces! (Only joking. The blood would drip, not spurt...)

Canford Audio not only sell a variety of different models of headphone limiter, but also offer a service for fitting BBC-designed passive limiters into individual pairs of headphones.
The basic point is that you need to be extra careful when using headphones. The source of sound is very close to the ear; you may be tempted to monitor at elevated levels to minimise the intrusion of external ambient noise; and you will not feel the physical effects of high sound levels which may, in turn, subconsciously encourage you to turn the level up even more. With the kind of high-output headphone amps now available in all manner of equipment, in combination with the use of low-impedance headphones, it is very easy to generate seriously high levels.
Naturally, a degree of common sense is required, but as human perception is easily misled I would recommend taking five- or ten-minute breaks every half hour or so to let the ear rest and re-establish a sensible reference level. Go and make a cup of tea, or go outside for some fresh air — whatever it takes to get you away from the studio for a while and let the ears recover. If, when you come back in, the headphones seem very loud, take that as a hint that you are monitoring too loud and are risking hearing damage! Obviously, there will be times, especially if you are editing audio tracks, that you need to crank the level up to make subtle artefacts more audible. Just remember to turn the level down again afterwards, both to get a realistic appreciation of the edit and also to preserve your hearing.
It is increasingly common in professional circles now to fit passive limiters to the headphones to ensure that the levels cannot exceed some predetermined level (typically between 85dBA and 110dBA, the actual figure being determined by the amount of time users are likely to be exposed to high-level sound). Canford Audio manufacture and fit such devices originally designed and implemented by the BBC. You can buy a few models of headphones with suitable units already fitted, including Beyerdynamic DT100s and Sennheiser HD480s, or can supply your own headphones to Canford, who will then test them, select the correct limiter device, install and calibrate it. I can thoroughly recommend these devices, although fitting the limiter can be as expensive as buying the headphones themselves on a one-off basis, so it may only be a viable proposition for those operating on a commercial basis, and with one eye on the Health and Safety regulations.
Choosing The Right Headphones
There are several variations on the theme of headphones, but the two principal types in use in studios and control rooms are closed-backed and open-backed. These terms refer to the mounting arrangement of the transducers within the headphones. A closed-backed headphone seals the transducer within its enclosure so that virtually no sound escapes to the outside world. Equally, little of the ambient sound gets in. This type of headphone is the best choice for the studio floor, enabling the musicians to hear what's going on without the headphone signal bleeding into the microphones.

These Sennheiser HD600s provide extremely high-quality sound for mixing purposes, but their open-backed design makes them unsuitable for many studio recording tasks, and their 'Y'-shaped cable requires more care when taking them off.
However, until relatively recently, most closed-backed headphones sounded pretty grim — boxy, dull, and lacking in air and openness. This is not really a problem when overdubbing or playing along with others, because it only has to provide a cue, after all, but making critical mixing decisions is almost impossible if the sound quality is poor. However, some of the more modern designs can produce a pretty respectable sound, and models worthy of consideration and auditioning include the AKG K271, Beyerdynamic DT150, Sennheiser HD250, and Sony MDR7506 and MDR7509. The last two models are particularly impressive, and I often use the MDR7509s myself when mixing on headphones.
The alternative open-backed headphone design has traditionally provided the best sound quality in headphone monitoring. The downside, of course, is that this kind of headphone spills quite a lot of sound into the local environment, and also provides little attenuation of ambient sound. Whether this is a real, practical problem depends on the particular circumstances. For late-night mixing, open backed headphones may be perfectly acceptable, whereas for location recording they probably won't be. The better options worth investigating here include the AKG K240, Beyerdynamic DT990, Sennheiser HD600, and Ultrasone HFI2000. I relied on the almost ubiquitous K240s for many years until replacing them with the HD600, but the Austrian model is still going strong in reserve!
It will come as no surprise that, in general, the better the headphone, the more it costs. For accurate mixing duties I would suggest pairs costing about £100 in the UK to be the practical minimum as far as quality is concerned, with the best models costing around twice that amount. While some may initially baulk at such a cost, in reality even £200 is trivial in comparison with a pair of decent studio loudspeakers and an amplifier of similar resolution.

Although closed-backed headphones often suffer sonically, the Sony MDR7509s shown here buck the trend, and would be a good choice for mixing duties. The single cable from the left headphone makes this model easy to put on and remove, but some users may find the pull from the curly cable on that side uncomfortable.
When purchasing headphones it is vital to bear in mind how comfortable they are to wear. When mixing you will be wearing the headphones for considerable periods of time, so it is worthwhile taking the trouble to wear the various models selected for your short list for a reasonable period of time, to get a true impression of what they will be like to work with. Also, make sure the headphones are adjustable to fit your head correctly. That they stay where you put them, and won't slide off when you look down. It can also be problematic if they are too heavy or if they squeeze the ears or sides of the head excessively. Models which don't make your ears hot and sweaty are worth seeking out, and replaceable earpads are a great advantage for cleaning purposes.
If you're investing in expensive headphones, then check that spare parts can be obtained easily, so that you can maintain your purchase should it become necessary in the years to come. Because headphones are pulled on and off, fall off the desk, and get stood on fairly frequently, some maintenance is only to be expected!
The reliability of the cable and connectors is obviously pretty important, although people disagree on what type of cable they prefer. Some people dislike curly extending cables on their headphones, mainly I think because they exert a considerable tension on the headphone when stretched and are heavier than ordinary fixed-length cables. However, I actually prefer this type of cable, provided that the curly section is long enough to remain unstretched during normal use. I find the extra stretch in the cable often comes in very handy should I have to move further away, and the plain cables always seem to form trip hazards for me!
There's also a choice between single-sided or double-sided cable entry to the headphones. I prefer headphones where the cable connection exits from one side only, purely for practical convenience. However, there is an argument that says this may be technically inferior because of the need to run an extra section of cable through the headband to the earpiece on the opposite side, through additional connectors or cable joints. In contrast, models with a 'Y' cord are more easily damaged, because sliding the headphones off backwards often results in the cable catching under the chin and straining the connectors to the earpieces!
Practical Mixing Tactics

If you're investing a bit of money in a pair of headphones for mixing purposes, then it makes sense to go for something with a complete set of spares. After all, headphones often come in for a fair amount of abuse in the home studio, and you don't want to have to replace the entire headset if only a single component needs repairing.
In practical terms, the most obvious requirement for mixing on headphones is to spend time getting used to your choice of headphones before mixing anything for real. Listen critically to a lot of commercial material. Get used to the different spectral balance of the headphones — many tend to sound a little brighter and thinner than conventional loudspeakers — and learn how to relate that to what you hear on the loudspeakers. Find out how the bass instruments sound on the headphones, in particular the way the fundamental and harmonics stand up and balance with the other instruments. Remember that some of the visceral low-frequency weight experienced with loudspeakers will be missing, so it's important to learn to appreciate the difference.
Because good headphones often have far lower distortion levels than loudspeakers, you may well find that low mid-range detail has far more clarity when auditioned in the headphones than over modest two-way loudspeakers. This may fool you into mixing critical mid-range instruments lower than they really need to be, or applying less equalisation than you would otherwise have done.
Mixing with headphones is a challenge, as they are inherently inferior to loudspeakers in many ways. However, these deficiencies are often outweighed by the practical considerations. With practice it is possible to create perfectly acceptable mixes from beneath the headphones, but, just as getting acquainted to the sound of an unfamiliar pair of monitors takes time and effort, headphone monitoring is an acquired skill that requires an alternative way of listening.
Published in SOS December 2003

Dam. Now I know..and knowing is half the battle. Now to another question: What the hell does mastering actually entail? What does it do for the mix? also..how is it accomplised?
Gimme a guide on that one! hehe

Dam. Now I know..and knowing is half the battle. Now to another question: What the hell does mastering actually entail? What does it do for the mix? also..how is it accomplised?
Gimme a guide on that one! hehe

Click to expand...

found one:
YOU'VE JUST COMPLETED the mixdown of the final track to go on your groundbreaking demo EP. You listen through your album several more times, but the more you compare it to your favourite CDs by the artists you admire, it always seems to fall short. It sounds dull and lacks impact, it doesn't flow right and, quite frankly, you're getting tired of hearing the same track over...

These feelings are shared by pretty much all of us involved with making music, including some of the best mixing engineers and producers in the world. This is why, prior to sending an album or single off for commercial CD or vinyl duplication, a lot of people pass their recording by a mastering engineer's keen ear to ensure it's technically suitable for release. Engineers possess both the tools and the complete understanding to make any necessary changes to present the music in its best possible light. This could involve any number of things, from dynamics processing for a heightened sensation of impact or spectral balancing using EQ for maximum high fidelity, through to bass and stereo enhancement or authoring for CD duplication. The mastering engineer is the absolute final check of quality before the music hits its target, whether that be record label A&R offices or even the retailers' shelves.

DIY or pro

With the explosion of the home studio generation in recent years, manufacturers have seen to the needs of budding wannabe engineers with a series of fairly affordable products to carry your musical vision from inception to completion, without ever having to set step inside a professional studio. So why is there such a strong emphasis placed upon having your music treated to a professional mastering service?
The immediate benefit is the mastering engineer's fresh set of ears. Unlike you, they haven't heard the tracks an umpteenth number of times, including its various stages of arrangement, remixes, or the parts that didn't make the album, so they can remain objective and hear it for its face value.

Mastering studios are equipped to pass your music through some of the finest equipment in the world. The odd cheap effects unit is fine on a single instrument, but hardly the sort of thing you'd trust your main mix through. Engineers know what things should sound like, and how to get it there. They'll also hopefully recognise when something should be left untouched, and not process for the sake of processing. But it is perfectly possible to do it yourself...

There are plenty of people producing favourable results with their own smaller studio set-ups. Being involved at every stage of the process, including mastering, is undeniably part of the attraction of owning our own gear. There's also the worry of placing your dream into the hands of a stranger. Your chosen mastering engineer must have an affinity and complete understanding of your vision, otherwise they're hardly going to be in tune with your expectations. However, by learning the craft of mastering, you'll come to understand what's required to make a tune sound great, and also the limitations.

Mastering should definitely not be considered the magical cure for a bad mix. "Don't worry about that mate, we can fix it in mastering," just isn't going to cut it in most cases. A great mix makes an even greater master. Practice your mastering skills on your demos. If you eventually move on to releasing your music commercially, still consider having your music professionally mastered, if only on an educational level to discover how you might further refine your skills. So allow me to show you how to begin doing pro-level mastering for yourself...

Listening in colour

Whether you listen in colour or in black and white can make all the difference to your recording, and though that may sound intriguing, let me explain. Take Spielberg's epic war drama Schindler's List, or any black and white film. The further your'e drawn to the characters and the storyline, the less your mind realises you're not watching in colour. The human brain compensates for any deficiencies you may see (a bit like when you can imagine you can see a full landscape, even though something like a pillar or a fence may be in the way). I've dubbed this perfectly natural phenomenon as the 'black & white effect', and it applies to music as well.

It's so easy to listen to a cruddy recording yet be totally touched by the musical genius of the performance. But if that performance is three minutes of a radio show, it's essential that it shines in all its colourful glory, or it will fall behind the competition. During the many months (sometimes years) of writing, recording and mixing your album, you tend to become so intimate with the musical storyline that it soon becomes impossible to make objective decisions in what could improve the recording, hence the mastering process. If you plan to be your own mastering engineer, you must always remain grounded to recognise this potential problem from its onset.

When mastering, carefully note any areas requiring immediate attention, and be wary of other issues creeping in right under your nose during the mastering process that may result in a substandard 'black and white' master. You have to work quickly. Listen, make an alteration if necessary, compare results and move on. If you get caught up trying to fix one problem for too long, take a break and come back to it when you're feeling fresh and able to make a fair judgement.

The mastering engineer's role is to create a sense of continuity. This may involve ensuring an album flows smoothly with regards to level matching and the transition between songs, or so each track will sit nicely alongside other independently produced and mastered material on radio, for example.

I was recently working on a mastering project for a new music label wishing to showcase their artists on CD in a continuous mix. So rather than just one artist's vision to work on, there were several, each with differing musical styles, and produced in different studios (some entirely hardware, another using only software-based synths and samplers), and varying levels of production.

Before I could even consider the DJ-like mix aspect of the job, I had to work through the tracks first and subtly touch up each one using my mastering tools. The end result was a product that enhanced the work of each artist, while still retaining the essence of their individualism, which would finally gel together as an album with a quality comparable to other compilations on the market.

Hard or soft

There are two trains of thought when it comes to the mastering format of choice. Traditionally, mastering was very much a hardware-orientated affair, calling on finely engineered analogue compressors and limiters, exciters, bass enhancement circuity and equalisation. Unfortunately, such gear is prohibitively expensive for most of us.

With the arrival of CD, the focus turned towards digital processing algorithms. For the PC or Mac-based home studio, this has lead to huge popularity of reasonably priced, standalone software applications and plug-ins that run within your audio software's environment. They offer a distinct advantage over their analogue hardware counterparts through their ability to instantly save and recall user set-ups. They also allow multiple occurrences of the same processor, meaning you can simultaneously run a new compressor on every track on an album, for example, with each one configured for the track in mind. Using hardware, you'd have to possess several units for this sort of flexibility, or be prepared to write down your settings as you move from track to track, and possibly feel less inclined to go back and make changes out of sheer inconvenience.

Still, things aren't necessarily rosy in the plug-in world either. Once you start to price some of the upper-end hardware, you'll no doubt see an immediate attraction to software, but there's more to it than mere economics. Most entry-level packages are bundled with an assortment of audio processing tools. In fact, with the VST platform being open to development by anyone, you'll stumble across plenty of freeware effects as well. These are generally fine for creative applications on individual sounds, but probably won't stand up to the stringent standards required for mastering your finished track. Instead they may result in a loss of depth and definition, and inflict an artificial digital character.

Third-party developers, whose core business relies on quality plug-in products, are a much better investment. The Waves collections (www.waves.com) in VST, DirectX, MAS, TDM and RTAS are particularly good for their highly musical yet transparent parametric EQs and multiband compression. Possibly their most dramatic mastering product is the L1 Ultramaximizer, which has often been referred to by users as "worth the admission price alone".

The L1 incorporates a look-ahead peak limiter (to capture ultra-fast volume spikes as they occur) with an automatic make-up gain for maximum volume potential, plus the appropriate dithering algorithms to reliably convert your 24-bit audio file down to a CD-friendly 16-bit. This plug-in will easily raise the apparent level of your material to a commercial standard, but can absolutely wreck the dynamic emotion of a performance if abused.

Do-it-all

An all-in-one package aimed at the home mastering market is IK Multimedia's T-Racks 24 (www.t-racks.com). Rather than relying on a host program to function, T-Racks 24 is completely free standing; just import your audio files in to the program and you're away. The emulation of valve-based analogue hardware is very much designed to colour your sound, albeit in a positive manner, therefore opinions on its worth in preserving the original recording in a mastering role are a little mixed. However, T-Racks users absolutely rave about it, and it might be of particular interest to those of you who use a lot of software-generated instruments and are looking to add a pinch of analogue character to spice up your recordings.

Another couple of quality mastering packages are Steinberg's WaveLab (www.steinberg.net) and Emagic's WaveBurner Pro (www.emagic.de). Both incorporate wave editors, VST mastering effects and CD burning facilities.And don't feel you necessarily need dedicated mastering software. The audio environment in your present audio sequencer should be adequate if the effects are up to scratch and may be auditioned and tweaked in real-time, rather than waiting for the entire file to be processed first.

In some cases, a mix of hardware and software is used, but bear in mind that every time music passes back and forth through the digital-to-analogue converters (DAC), degradation to the waveform is inevitable. This is a strong reason why professional studios employ precision converters from the likes of Apogee (www.apogeedigital.com) and Prism Sound (www.prismsound.com) to interact their digital audio with the outside world. Perform some critical listening tests with your own equipment. You may find it best to remain in the digital realm, if only to avoid the digital-analogue headache, but also due to the average analogue rack gear being far from noiseless in itself.

The hard way

Lastly, there are a number of hardware-based digital processors available that are packed with essential mastering tools. They're like the best of both worlds: custom DSP (digital signal processing) chips mounted within a sturdy rack chassis. Examples include the dbx Quantum and Quantum II (www.dbxpro.com), Drawmer Masterflow DC247(www.drawmer.co.uk), and the ever-popular TC Electronic Finalizer Express and Finalizer 96k(www.tcelectronic.com). These devices are an excellent solution for situations where a computer isn't appropriate (such as live performances) or for those looking for a product that offers superb quality, straight out the box, with a minimum of fuss.

If you're using the processor in conjunction with your computer, it's essential to take advantage of the digital connections to avoid an unnecessary analogue conversion. Be wary of the seemingly preset nature of these boxes, as mastering is never a preset process. Like all aspects of music production, it's a matter of getting in beyond the presets and working the settings to discover your own magic formula that works in harmony with the material you're mastering.

Your audio monitors act as a magnifying glass and finetooth comb for picking out any errors and inconsistencies in your audio material, allowing you to correct it prior to duplication and commercial distribution. In a typical mastering house, the popular nearfield monitors we often find ourselves mixing on are nowhere to be seen.

In favour are the larger (and considerably more expensive) full-range main monitors, such as the Genelec 1035B (www.genelec.com) or Quested HM212 (www.quested.com), that offer unsurpassed levels of clarity,imaging, dynamics, and a frequency response that just isn't available to the smaller nearfield market. Often found soffit-mounted (flush to the wall), these monitors fire into a control room that's been acoustically optimised to minimise reflections, distortions, and resonances.

Of course, most of us can only dream of ever working in such a pristine environment, so you have to make the most out of your current monitoring set-up. Ideally you shouldn't be mastering on the same set of monitors that were used for mixing, otherwise rouge nasties may slip through the net without being noticed, so, at the very least, a secondary speaker system should be available, alongside your primary monitors.

Get to know how music sounds on a range of speakers, such as multimedia speakers or the popular Auratone Cubes (to emulate the typical television and small radio) and bigger hi-fi systems. If you're preparing music likely to be played in nightclub, be wary of over-hyping sub bass frequencies due to the inadequacies of your present monitors.

This is where a mate's megaWatt, stereo-on-wheels, car audio system could come in handy. The more references you have access to, the better. This helps you predict how your masters in progress will eventually translate on your intended audience's wide range of playback systems.

Next comes the room itself. Forget the speaker manufacturer's advertising blurb and technical specs for a moment; stop and listen to how the room sounds. Walk around and observe how sounds change throughout the room. These acoustic variations, caused by soundwaves collecting and reflecting, and rising and falling throughout the room, are perfectly natural phenomenons, yet can heavily influence the decisions you make during your track mastering. In my own studio, I discovered a mid-bass resonant peak after critically listening to numerous recordings I was familiar with. If I ignored it, I might have risked removing these frequencies during mixing or mastering through equalisation, so I rearranged my set-up by repositioning my workstation and monitors a little towards the centre of the room until I felt everything sounded more natural.

Are there any improvements you can make to your own monitor placement? Be aware of the room walls, floors, corners and ceilings that may be hyping bass frequencies, and note any hard surfaces that can reflect and smear mid and upper range frequencies. Sometimes it may be simply a matter of installing a set of heavy curtains over a window, or shifting a couple of racks of equipment. Most monitors are magnetically shielded to protect computer and TV screens from picture distortion, but also have a think about how your soundwaves may be bouncing off the sides of your computer monitor screen.

Mastering your meters

Mastering requires highly accurate level metering. The LED meters found on most mixing desks, as well as the displays in audio software, are generally set to track the fast travelling peak of the audio waveform with precision.

While this is essential for keeping a watchful eye on clipping when recording digitally by exceeding 0dBFS (FS = Full Scale, the maximum level a waveform may be encoded digitally), program peak metering does not relate too well to the real world. Our ears tend to respond to the slower, average volume level, while the ultra fast transients go unnoticed. Two songs with identical signal peaks may appear different in volume simply because one of the songs average level was lower. This is why analogue VU meters are still popular among studios because they give a good representation of how the human ear perceives volume.
Look for an RMS setting on your digital level meter, such as the PAZ Psychoacoustic Analyzer (www.waves.com) plug-in for Mac to get a real world idea of the average volume. Most people strive for a loud mix, but be wary of setting your average level too high. Apart from becoming fatiguing to listen to, you may run into problems in radio broadcast situations where the station's limiters confuse the main energy of your track with the instantaneous peaks and attempt to squash it further. As a general rule, the difference between your peak levels and your average levels (known as the peak to average ratio) should never be less than 6dB.

One final point with metering: although it makes a terrific reference, a level meter is still not perfect. It registers evenly across the entire audio spectrum, whereas our hearing is more sensitive to mid-range frequencies, so always let your ears make the final verdict.

Another couple of worthy features from the PAZ plug-in are the Spectrum Analyzer, to visualise how energy levels are distributed among the audible frequencies (handy for comparing bass levels between different songs, for example); and the Stereo Position Display which also deciphers out-of-phase material. For a quick phase demonstration, reverse the polarity of the wires connected to just one of your stereo speakers (connect positive to negative, and negative to positive) and play back some music through them. Note the sensation of extreme width, minimal bass, and an obvious hole in the centre of the music. This is the due to the left and right channels working 180° out of phase from each other. The cones are literally pushing in different directions.

Sometimes, a sound can be thrown out of phase while recording or mixing if a channel is delayed for a stereo effect, or a studio cable or patchbay is wired incorrectly. Should the out-of-phase material be played through a single speaker set-up (like a television, for example), the true mono component of the audio would completely cancel out and become inaudible. So, be wary of out-of-phase sounds in the mix, and if in doubt, check it on a monaural source for compatibility.

Setting up

In order to get set up, the first step is to prepare your tracks for the session (see the Step-by-step #1 box on p113 for more on this). Close down all unnecessary computer applications so the CPU's clock cycles are available solely for music reproduction and accurate on-screen level metering. If you're accepting mastering jobs, ideally the tracks should be supplied on DAT or CD-ROM. Even portable hard disks are common these days. Audio on CD-R may be used, but is best avoided due to lost bits of data being unaccounted for during the ripping process when returning the CD back to a computer file.

Encourage your customers to supply their material without any main bus effects processing like compression or normalisation, and have them retain the same bit depth and sample rate that their mix was created in.

Every time a file is converted from a higher bit/sample rate down to 16-bit/44.1kHz (CD format), there is some degradation, either through truncating the extra bits from each word, or from the preferred approach of dithering. I personally mix in 24bit/44.1kHz and stay that way until the final stage of mastering when I'm ready to commit to dithering down to 16-bit.

Hearing is believing!

On a final note before delving into the actual process of mastering, you must consider the most important piece of test equipment in the studio: your ears. Every decision you make will be run past your ears for analysis, so there's a lot of responsibility riding on your ability to hear things as they really are.

Unfortunately, our quality of hearing fluctuates throughout the day, particularly after loud or extended listening periods, and when we're feeling tired and stressed, so always devote a fresh day to mastering. You may also wish to consider having your ears tested professionally, which would be a very good idea if you're setting out on a career in mastering.
Before starting a session, pop on a familiar (and professionally mastered) CD that compliments the style of music you plan to be working on. Don't monitor too loudly or you'll spoil your ears before you've even started! While listening, note the bass presence and definition; the prominence of the vocals, synths or guitars; and the detail of the cymbals and other treble in the mix. Observe your level meters: watch where the peaks of each beat sit, as well as the quieter periods of the piece. These practices serve to calibrate your hearing by placing a fresh reference in your mind of what things should sound like, in living colour!

Final advice

Maintain moderate listening levels. Once you think you've nailed a setting, turn it up to full room level and see if everything still sits right, before bringing your monitoring level right back down again to preserve your hearing's sensitivity. Always refer back to your reference material throughout the session to ensure you haven't steered off track into 'black & white' territory.

Listen for the message the composers are putting forth. They're ultimately the creative forces behind the music, and it's your role as the mastering engineer to enhance their original vision by working in harmony with it.

Although mastering is very much a technical process, the fundamental settlement of each mastering decision falls squarely back on your understanding and love for music as an artform. This appreciation continues to grow throughout our lifetime, allowing each of us us to broaden our proficiency at mastering through experience.

A guide to setting up a mastering session for an album in Pro Tools. Apply the same principle to any multitrack audio sequencer with real-time effects...

1.Open a fresh session with sufficient stereo tracks to cover the songs
you plan to master, plus another for your reference track. This point of reference should be a piece of professionally produced and mastered music that you aspire to, and in the same genre as the tracks you're mastering.

2.Add the insert effects you might use for mastering. Although you might not end up using every one as it really depends upon what you feel each track requires, I like to set up the most commonly used tools. A few examples are a parametric EQ, stereo enhancement, a multiband compressor, and limiter.

3.Listen through all the tracks first, and make careful notes to ensure nothing is overlooked. Go back to you reference track to calibrate your senses, then work on the track that you feel is already close to perfection. Use this track has an example of where the remaining tracks should be steered towards.

4.Work your way through the tracks making subtle changes if required. Compare them to each other to ensure they're of uniform consistency, and of course how they stack up against your reference track. The PAZ Analyzer comes in handy for comparing volume levels and frequency content, but your ears should always be the final judge.

5.Trim the starts and finishes of each track. It's a very good idea to insert at least 100ms before the start of each track to ensure the first beat or note is not missed by some CD players that mute their output for several milliseconds upon playback. Add any fade ins or fade outs. It's crucial the fades take place after the compression or limiting, otherwise the change in level beforehand will upset the processor's response.

6.Take the opportunity now to listen to how each track will flow into the next as they will eventually appear on the finished album. Adjust the relative volume of each track to suit, using your ears, not necessarily your meters. Bounce each track (including the effects) as a separate file to disk, not forgetting the blank portion before each track starts. Load up your CD burning software, add your tracks, set the gap between each song to taste (commonly two seconds), and burn CD using the Disk At Once setting (and not Track At Once).

STEP-BY-STEP #2: Sorting out the EQ

For accurate equalisation with pinpoint precision, you'll need a multiband parametric EQ that offers full control over the frequencies...

1.Place the EQ first in the chain of mastering effects. This ensures subsequent processing (eg, compressors) won't respond to frequencies that have since been removed. Start by setting a high-pass shelving filter to around 30-35Hz. This eliminates the subharmonic content of the music, and can actually improve the bass definition by returning lost amplifier power and minimising speaker instability caused by frequencies below their limits.

2.A neat trick to bring out certain instruments and improve clarity is to slightly notch out the frequency immediately below the instrument you want to bring out. Watch out that you don't take out the body of the mix though. It is very much a juggling act; a sharp dip somewhere between 150-300Hz may help reduce a muddy mix, while gradually peaking up above 8kHz may provide some high fidelity air. Don't concentrate on specific instruments though, just the overall tone of the music. Use a high Q setting to focus in on a narrow band of frequencies, or a low Q to cover a broader range of frequencies.

3.Go back to your reference CD and make comparisons. There's no preset formula for the right EQ, and if the track's been mixed well, you should be able to leave it alone. You are more looking to gently nudge the EQ into place by a few dB, rather than a surgical operation. Should any problem frequencies ring out too much, locate the exact frequency by sweeping a filter peak up and down the audio spectrum until the offending frequency stands out more, before reducing the EQ back down at that point. Compare your EQ with the effect bypassed to ensure your changes are beneficial.

STEP-BY-STEP #3: Multiband compression

For transparent compression resulting in a louder mix with minimal pumping effects, you might find it's better to use a compressor that treats different frequency bands of the audio spectrum separately (on these pictures, we've shown a TL Audio Ivory compressor)...

1.Before considering a multi-band compressor, you should be well accustomed to using a regular single-band device. Refer to The ultimate guide to compression feature from FM114. When placed across an entire mix, a compressor's job is generally to lift the overall perceived volume of the music and can also help create a tight and more defined mix. It works by restricting the fast volume peaks in the music. This in turn allows you to turn up the output resulting in a louder sounding mix whilst the peaks are kept safely under control. NB: The dynamic range (ie. difference between loud and soft musical passages) will be reduced by compression.

2.A multiband compressor is two or more compressor circuits working alongside each other, but set to concentrate on their own section of frequencies. Start with a compression ratio (comp) of 2 or 3:1 on all bands, although you may choose to increase the lowest band up to 4:1 for dancefloor-based music. The ratio determines the degree of gain reduction. For example: 1:1 means that the volume remains unchanged; 4:1 means that for every four units of volume that enters above the threshold, there'll be just one unit of volume at the output.

3.Start with the lowest band (the bass) and lower the threshold (circled) until about 3dB of compressed signal is registered on the gain reduction meter. Then raise the output gain for that band to compensate for the loss of volume incurred by the action of the compressor.

4.Now lower the threshold of the next band until about 3dB of gain reduction is registered, and raise the output (circled) to compensate. The upper band(s) covering the treble frequencies will probably require no compression, so just lower the threshold to catch any peaks, although slight high frequency compression can be desirable to emulate tape saturation.

5.You'll find that the EQ balance across the mix will now be all over the place as the volume of each band has been altered. To readjust, use the output gain controls on each band, bypassing the compressor at times to check for the original tonal balance.

6.Go back and listen carefully for transients in the music like the thump of a kick drum, or the crash of a cymbal. How do they sound before compression? Is the change for the better? They should still retain their dynamics without restraint. Increase the attack portion(s) of the compressor to allow more time for the initial peaks of these instruments to pass through, or lessen the threshold or compression ratio.

STEP-BY-STEP #4: Using the Waves L1 plug-in

The Waves L1 Ultramaximizer plug-in is an excellent yet simple way to dramatically lift the perceived volume of your music. It should be the last thing you do to your track in the mastering process...
1.L1 is capable of pushing the waveform peaks extremely close to the maximum digital limit of 0dBFS (Full Scale), meaning further alteration to the volume following the L1 (eg, compression or EQ) may result in clipping/distortion of the waveform. Also, the L1 can implement a dithering routine to smoothly convert from say, a 24-bit stream to16-bit, ready for CD duplication. For these reasons, always place the plug-in last in your effects processing chain.

2.Set the Out Ceiling no higher than -0.5dB. This controls the automatic make-up gain that compensates for the reduction in output due to the action of the limiter. Basically, this sets the level your music peaks will leave the limiter at. It's a good idea to not set this to the maximum (0dBFS) in case some peaks still get through, or is read by some CD players as a digital overload. Now pull down the Threshold and observe your music becoming louder. Compare your average volume increase to that of your reference material. While this plug-in is nothing short of amazing, listen carefullly for over-compression taking the life out of the performance making for a very fatiguing listening session, and heavy abuse of the threshold will generate audio distortion.

3.Choose the Quantise bit rate for your destination. Whenever you move from a higher wordlength to a smaller wordlength, the file should be dithered for the cleanest conversion. For example, if you recorded and mixed in 24-bit, stay this way until you've completed your mastering and you're ready to dither your 16-bit file for CD. If you were originally working in 16-bit, you can convert to 24-bit for mastering, and then dither your file back to 16-bit. Due to the degree of noise introduced, the dithering process to 16-bit should only be performed to the file once.

I will read all of that, I will read all of that,
I will read all of that, I will read all of that,
I will read all of that, I will read all of that,
I will read all of that, I will read all of that,
I will read all of that, I will read all of that,

screw it, I'm printing this badboy out and one day during a dump, I will learn how to master my tracks and such!